Refining process



montos Apr. s, i943 UNITED `STATES 'PATENT OFFICE mamma rnocsss v Elson E. stably, Boton Bongo., La., nssignor, by mesne assignments, to Jasco, Incorporated, a corporation o! Louisiana sppiioouon January es. i940, serial No. 315,495

, a claims (corsa-115) The present invention relates to the reilning of mineral oils. The invention is particularly directed to a method oijreiining gases derived in y the processing ot petroleum oils by which it is `possible to economically segregate the gases into their respective constituents which are generallyl utilized as intermediate agents for the produc` tion of additional valuable products.l In accordance with the present process, unsaturated hydrocarbon gases are segregated trom saturated hydrocarbon gases by treating gaseous mixtures containing the same, preferably in afcountercurrent manner, with a liquid solution of a high molecular weight substance secured by the polymerization of -relatively low molecular ,weight hydrocarbons.

In the processing oi stances to segregate various gaseous lluyproducts and to use thesey fractions as intermediate feed stocks for the production of additional valuable products. For example, it is desirable to segregate gases'secured in the refining of petroleum,

gaseous o mon practice is to employ various solvents which.

exhibit 'a preferential selectivity for' either the saturated or unsaturated constituents and then to subsequently recover the 'dissolved material.

I have now discovered-aproces's employing a particular solvent by which it ispossible to eco-4 nomically `and eiiidentlyproduce gas fractions containing 1|. relatively concentration ot oleiins from 'the same. The process oi niy invention -absorbing the unsaturated` minerai ous, vmirtiouiiurly petroleum oils, it is very desirable Iinmany in is taken to be a pentane solution of a high molecular weight substance secured by polymerizing butene under conditions to produce a polymerized product having a molecular weight in the range above about 30,000. The solvent solution is introduced into the top of countercurrent treating tower I by means of feed line 2. The solvent solution ilows downwardly through tower I and contacts upowing gases which are introduced into tower i by means of feed line I. 'Adequate contact between the countercurrently ilowing phases is secured by 'suitable distributing and contacting means such as bubble cap plates,

pierced plates, contact masses, and the like. Temperature and pressure conditions are maintained on tower I adapted to secure amaximum absorption"V o! the unsaturated hydrocarbons.

The treated gas mixture is withdrawn from tower Il by means' of line 4 and handled inl any manner desirable. These gases mayebe cooled in cooler 5, compressed in compressor 6, and returned to the system` by means ofl line 1 -orremoved by means of line il and disposed of in any manner desirable. The solvent solution containing thedissolved unsaturated hydrocarbons is removed trom the bot-v tom of tower i by means 'oi line I and handled in a 'manner to recover .the dissolved hydrocarbons from the solvent solution. lIfhis may beaccomplished in any desirable manner. However, in accordance with my invention, the preferred method is to utilize a two-stage distillation opero ation;4 This is accomplished by v`introducing the solution removed fromv tower l bymean's of line I, into initinldistillation stage l0. Temperature and pressure` conditions are' adjusted so' that a relatively small per cent of the gases dissolved is removed overhead from distillation unit l0 by P means ot line'll. I have found that these gases uente iromaseous mixtures containinirftlie same, utilizing as aselective l o solvents solutions: a sous-nigh moieo'iuanweiabt substance secured bya relatively low molecular weight hydrocarbon. The'process oi my inv'entionis a continuousone.

It is also desirable that the absorbed hydrocarf bons be vrecovened from the solventin a twoo stagedistillation operation. l

The process oi my invention may be readily understood by reference to the attached drawing illustrating one modlilcation of the-same.l The sclective'solvent. ior the purposes o! illustration,

44are relatively rich in saturated hydrocarbons.

@The solution is removedirom distillation unit Iii 'by meansoi' line I2 and introduced into the secondary distillation unit il. -Temperature and' pressure conditions -are adjusted in distillation' unit i! adaptedto substantially completely re# cover the" dissolved gases which are' removed overhead ,by means lof line I4. The solvent solution is removed trom'distillatlon unit I3 by means of line Il andpassedto solvent storage it, from whichit mayberecycled to towerl by mean's'o! line i1;l Fresh *solvent means oi line i8.

The solvent mixture of my invention comprises a solution or. nigh moiociuanweignt substances secured by the polymerization oirelatively low molecularweight hydrocarbons. Preferr'ed solmay be .introduced by vents are solutions of substantially saturated high molecular weight hydrocarbon polymers having molecular weights in the range from about 1,000 to 300,000, preferably in the range of above 30,000. 'I'hese polymers are characterized by having a relatively longv hydrocarbon chain, the carbon atoms of which are all completely saturated with the exception of a single double bond or relatively few double bonds. The molecular weights of the solid solvents of the present invention are determined by the method -described in Staudingers book, Die Hockmolekularen Organischem Verbindungen, H. Staudinger Berlin 1932 Verlag Von Juluis Stringer, page 56. The solvent polymer compounds of the present invention are prepared by polymerizing substituted unsymmetrical alpha olefins, especially iso-mono-olen hydrocarbons, as for example, isobutylene, isoamylene, and the like at low temperatures in the presence of an inorganic halide catalyst. The temperature of polymerization is preferably below C., preferably in the range below -30 C. or even lower, depending upon the particular catalyst or other reaction conditions employed. As a catalyst, boron fluoride has been found particularly satisfactory. Also, boron uoride mixed with hydrogen fluoride may be used, as well as phosphorous or antimony triuoride or pentafluoride and aluminum chloride, the latter preferably being in the radiant state as obtained when aluminum is acted upon by hydrogen chloride. In the case of aluminum chloride 3% to 5% of the catalyst may be used, whereas in the case of the previously mentioned boron fluoride catalyst 1% or so may be suiicient. Also, solutions or double compounds of said halides such as with phenol,

cresol, and the like may be used. In the polymerization operation, suitable diluents may be used. preferably a volatile material such as pentane or a commercial naphtha which can be readily driven off, if desired, after completion of the polymerization. Inasmuch as such polymerizations are lusually exothermic, it is,` generally desirable to provide some means of cooling the reaction chamber, either externally or internally, as by the use of cooling coils or by the evaporation of a liquefied gas such as propane, etc. The molecular weight is readily controlled by regulating the temperature and duration of the polymerization operation. In general, the higher the molecular Weight the less sticky and tougher and harder is the polymer. l

As a particular example of. a preferred method of preparing such va polymer, isobutylene is polymer-ized at a temperature of about 10 C. by bubbling boron fluoride gas through a solution o! isobutylene dissolved in liquefied propane. 'When the molecular weight reaches about 10,000 or 15,000 the reaction is stopped and any catalyst remaining dissolved or suspended in the liquid is removed by washing the reaction product with water or dilute caustic soda. The volatile solvent is then removed by distillation, leaving a colorless plastic polymer as residue. This polymer is` somewhat tacky and plastic, is soluble in hydrocarbon solvents and mineral oils, is insoluble in water, is quite resistant to oxidation, and does not harden substantially with age as do some materials which have a fairly high content of unsaturated linkages. My polymer solvents have iodine numbers in the range below about fifteen, often as low as three or iive or lower. When freed of unsaturated low molecular weight bers generally do not exceed a .value of ilve as determined by the Hanus method. For example, a polyisobutylene product having an average molecular weight of about 13,000, comprising substantially no constituents having molecular weights below about 10,000 and which was purined by precipitation from a solution with dioxan, had an iodine number of 4.7 (cgs. I/gm.). Another polyisobutylene product having an average molecular weight of about '10,000 and comprising substantially no constituents having rmolecular weights below about 40,000 and which was purled by precipitation from a solution with liquid ethylene, had an iodine number of 1.6. As the polymerization reactionvproceeds, the degree of unsaturation is gradually reduced.

A satisfactory solvent for the present invention comprises a solution of a co-polymer product. These co-polymers may be produced by polymerizing a mixture of iso-mono-olen hydrocarbons, as for example, isobutylene and a dioleiln product, preferably a conjugated diolen, as for example, butadiene, isoprene, dimethyl butadiene, and the like. 'I'hese co-polymer products are similarly prepared at relatively low temperatures, using Friedel-Crafts and similar catalysts. in any suitable solvent. Preferred solvents are relatively light petroleum oils, as for example, petroleum oils boiling in the motor fuel and kerosene boiling range. Other desirable solvents are relatively pure hydrocarbons or mixtures of relatively pure hydrocarbons, as for example, isopentane, isobutane,.isohexane, and the like. The amount of polymerized product dissolved in the solvent will depend upon the particular polymerized material used, the particular solvent employed, as well as upon the character of the feed gases, operating conditions and upon the yields desired. In general, when utilizing a polymerized product having a molecular weight in the range above 30,000 and utilizing a hydrocarbonlsolvent boiling in the motor fuel and keroseneboiling range, it is preferred to use from 1% to 25%,

. preferably from 5% to 10% solution.

ume of gases being treated will likewise vary within wide limits and will be a function, to some extent, of the particular solvent used, the solution concentration, and the character of the feed gases. In general, the quantity of treating solution is from one volume to ten volumes of solution per volume of bases being treated. The distillation conditions for the irst distillation stage are adapted to remove approximately 20% to 40% and generally not over about 50% of the dis- .solved constituents from the solvent solution.

These conditions, depending upon general operating conditions, will vary considerably. For ex- Exnnma A gaseous feed mixture of butanes and butenes w'as countercurrently extracted with isopentane These polymer products may be dissolved The volume of solvent solution used per volof these experiments were as follows:

Table 1 Experi- Experiment I ment II Solvent solution, percent oi high molecular weight polymer. Distillation temperature first stnge F s( ler cent unsaturates:

Feed gases Gases removed from second distillution Increase From the above it is apparent that the present process is particularly adapted for producing gas fractions having a relatively high concentration of unsaturates. Additional stages may be employed to produce substantially pure unsaturated fractions. Recycling of various fractions or the use of diiuents and the like may also be utilized to improve the eillciency of the operation.A

The process of the present invention is not to be limited by any theory or mode of operation,

urated constituents from feed gas mixtures containing the same, comprising treating said feed gas mixtures, with a solvent solution of a high molecular weight substantially saturated polymer product produced by polymerizing relatively-low molecular weight olefinic hydrocarbons,

under conditions to selectively dissolve the un-` saturated constituents, separating the solvent solution and recovering' the unsaturated constituents therefrom.

2. Process in accordance .with claim 1 in which said polymer product is produced by polymeriaa lng butenes.

3. Process in accordance with claim 1 in which said polymer product has .a molecular weight/in excess of about 30,000 and which is produced by polymerizing isobutenes.l

4. Process in accordance with claim 1 in which I said solvent solution comprises a light petroleum oil having dissolved therein from 5% to 20% of a polymer product having a molecular weight in excess of about 30,000, said polymer product being produced by polymerizing isobutenes.

5. Process for the production of gas`fractions having a high concentration of unsaturated constituents from feed gas mixtures -containing the same, comprising countercurrently treating said feed gas mixtures in a countercurrent tower, with a solvent solution which comprises a high molecular weight substantially saturated polymer product produced by polymerizing relatively low molecular weight olenic hydrocarbons, under conditions to selectively dissolve the unsaturated.

hydrocarbon constituents, removing treated gases from the top of said tower, removing the treating solution containing the dissolved hydrocarbon constituents from the bottom of said tower, subjecting the same in-an initial distillation stage to conditions adapted to remove a minor amount of the dissolved hydrocarbons, removing the treating solution from said linitial distillation stage and subjecting the same in a secondary distillation stage to conditions adapted to substantially completely remove dissolved hydrocarbons from said treating solution whereby a gas fraction relatively rich in unsaturated constituents is evolved, removing said treating solution from the bottom of said secondary stage and recycling the same to saidcountercurrent treating tower, removing said gas fraction from the top of said secondary distillation stage'and recovering the same.

' 6. Process in accordance with claim 5 in which said high molecular weight substantially saturated polymer product has a molecular weight in excess of about 30,000.

7. Process in accordance with claim 5 in which said solvent solution comprises a light hydrocarbon solution of from 5% to 20% of a high molecular weight substance produced by polymerizing isobutylene.

8. Process in accordance with claim 5 in which from 20% to 40% ot the dissolved gases is removed in said initial distillation stage.

' Y ELDON E. BTAHLY. 

